Impact energized sound source



Sept. 11, 1962 H. E. SAWYER 3,

Mk 1\ N IN VEN TOR. HAROLD E .SAWYER ATTORNE Y5 3,653,220 lit/[PACT ENERGIZED SOUND SQURCE Harold E. Sawyer, Falmouth, Mass, assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Jan. 10, 1956, Ser. No. 558,392 13 Claims. (Cl. 116137) This invention relates to a sound source, and more particularly, to an impact energized sound source for creating acoustic signals of high intensity and short duration.

There now exist numerous devices capable of creating acoustic signals by means of impact action. These include striking a bell, disc, rod, diaphragm or other form of elastic body or vibrating system. However, a general characteristic of all these presently existing devices is the excitation of numerous modes of vibration of varying intensities. The particular relationship existing between these numerous modes of vibration depends upon the specific device employed.

The principal disadvantage of all existing devices for creating acoustic signals by means of impact action is that the available energy is distributed over several modes of vibration in some of which certain portions of the radiating surface may be mutually out of phase. Furthermore, in most of these devices the area of impact is small compared to the area of acoustic radiation and, therefore, radiation intensity is limited by the inelastic deformation of the surfaces of contact under excessive pressure.

The impact energized sound source contemplated by this invention employs a piston and an impact rod both of which have the same diameter and have their contacting surfaces ground to match each other. Therefore, any deformation of the radiating surface of the load is relatively small. In addition, the matched contact surfaces are maintained parallel to one another both prior to and upon impact of the impact rod with the piston. The cushioning effect of air between contact surfaces is greatly reduced by enclosing the impact rod and the contacting surface of the piston in an evacuated housing. This minimizes the time interval required to develop full impact pressure upon impact. Consequently, the rate of energy transferred from impact rod to piston is higher than has heretofore been obtained and the duration of contact, which should be less than one quarter of a period of vibration of the piston system, is substantially reduced, thereby making it possible to obtain a higher frequency of vibration than was formerly possible. Thus, because of the increased rate of energy transfer, shorter period pulses are possible and consequently a greater radiation intensity will be accepted by the medium of sound transmission than in the case of continuous or lower frequency radiation. Furthermore, the mass of piston and impact rod may be chosen to improve the impedance match at the fundamental frequency of the impact rod-piston system.

It is therefore an object of this invention to provide an impact energized sound source in which the contact surfaces of the piston and impact rod are matched and are maintained parallel, to thereby uniformly distribute the impact action over the entire piston area.

It is a further object of this invention to provide an impact energized sound source in which the contact surfaces of the piston and impact rod are enclosed Within an evacuated housing to thereby reduce the air pressure the contact surfaces and thereby reduce the cushioning effect produced by such air pressure.

It is a still further object of this invention to provide an impact rod whose mass is equivalent to the sum of the piston mass and the effective mass due to radiatio reaction of the piston.

It is a still further object of this invention to provide an impact energized sound source wherein the mass of the driving mechanism for the impact rod is excluded from participation in the impact action.

It is a still further object of this invention to provide an impact energized sound source employing a novel loading and releasing spring driving mechanism whereby the loading mechanism may be cleared from reaction with the spring driving linkage after release.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better under stood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

The sole FIGURE is an elevation view, partly in section, of an embodiment of the invention.

Referring now to the drawing, there is shown in section a housing 10, which may be partially evacuated. A steel piston '12, which in the preferred embodiment has a diameter of about 10 centimeters, is oriented in an opening at the top of housing It and is supported by means of a ring spring 14 which is secured to housing 10.

A cylindrical impact rod 16, having the same diameter as piston 12 and constructed of the same material as piston r12, and of much greater axial length than the thickness of said piston, has its upper surface, which makes contact with the lower surface of piston 12, ground to match the lower surface of piston 12. Impact rod 16 is floatingly supported by thrust plate 18. This floating support is a lost motion connection and is achieved by means of shouldered shaft 20, which is integral with impact rod 16 and is coaxially disposed with respect thereto. shouldered shaft 20 passes through a centrally located opening in thrust plate 18. The shoulder of shouldered shaft 20, which has a diameter which is too large to pass through this opening lies in a recess in the bottom of thrust plate 18. The aforementioned opening in thrust plate 18 is of suflicient tolerance to allow impact rod 16 to be longitudinally movable with respect to thrust plate 18, the shoulder or shouldered shaft 20 limiting the maximum amount of longitudinal movement thereof.

In order to ensure that impact rod 16 can move only in a longitudinal direction without any wobble, so that the matched surfaces of impact rod 16 and piston 12 are exactly parallel at all times, three guide rails 22 are provided. These three guide rails are oriented at an angular spacing of relative to each other in the horizontal plane. Base plate 24, located toward the bottom of housing 10, supports all three guide rails 22. Each of guide rails 22, which pass through a correspondingly oriented notch in thrust plate 18, is in lightly rubbing engagement with the cylindrical surface of impact rod 16.

Centrally located in base plate 24 is bushing 26. Passing through bushing 26 is hollow shaft 28. iI'IOllOW shaft 28 has an elongated longitudinal slot therethrough, as shown. Fixedly secured to thrust plate 18 are two pivots 30 and 32, respectively. The upper end of hollow shaft 28 is fixedly secured to these pivots 30 and 32, and thereby fixedly secured to thrust plate 18.

Rotatably mounted on pivot 30 is shaft 34 and rotatably mounted on pivot 32 is shaft 36, as shown. Shaft 34 telescopically fits into shaft 38 and shaft 36 telescopically fits over shaft 40. Shaft 38 is rotatably mounted on pivot 42 and shaft 40 is rotatably mounted on pivot 44. Pivots 42 and 44, respectively, are fixedly secured to opposite sides of housing 10 and are located, as shown, above base plate 24. Collars 45- and 47, integral with shafts 34 and 38 respectively, form stops for compression spring 46 mounted as shown over telescoping shafts 34 and 38. In a similar manner, compression spring 48 is mounted over telescoping shafts 36 and 40 between collar 50 integral with shaft 40 and a collar integral with shaft 36 which is not visible in the drawing.

A drive rod 52, only a portion of which is shown in the drawing, has one end thereof inserted into hollow shaft 28 and is fastened thereto by means of pin 54 which passes through the longitudinal slot in hollow shaft 23, as shown. The other end of drive rod 52, not shown, is connected to a load means such as the armature of a solenoid or any other means for pulling drive rod 52 in a downward direction.

As shown, the diameter of thrust plate 18 is greater than that of piston 12 and impact rod 16. A narrowing of the internal diameter of housing 10, as shown in the upper region 56 thereof, forms a stop for thrust plate 18.

Referring now to the operation of the impact energized sound source just described, drive rod 52 is moved in a downward direction by loading means such as a solenoid, not shown. This causes pin 54 to engage the lower end of the longitudinal slot in hollow shaft 28, pulling hollow shaft 28 in a downward direction. Since hollow shaft 28 is connected at its upper end to thrust plate 18 by means of pivots 3i) and 32, thrust plate 18 is also moved in a downward direction. Guide rails 22 passing through notches in thrust plate 18 maintain thrust plate 18 in a plane perpendicular to its longitudinal direction of travel. Impact rod 16 is also pulled in a downward direction by means of shouldered shaft 20 which contacts the undersurface of thrust plate 18. Guide rails 22 which are in rubbing engagement with the cylindrical surface of impact rod 16 maintain impact rod 16 perpendicular to its longitudinal direction of travel.

The motion of hollow shaft 28 and thrust plate 18 in a downward direction causes shaft 34 to telescope with shaft 38 and shaft 36 to telescope with shaft 4%). This in turn causes both compression springs 45 and 48 to be compressed. Since base plate 24 is located below a line connecting pivots 42 and 44, when pivots 30 and 32, respectively, are moved in a downward direction to a point beyond this line, a toggle-type reaction will take place and shafts 34 and 36 will be moved by the potential energy of compression springs 46 and 48 to a new stable position in contact with bushing 26.

The impact energized sound source is now in its loaded position.

The impact energized sound source is released by moving drive rod 52 in an upward direction until pin 54 contacts the upper end of the longitudinal slot in hollow shaft 28, and then moving hollow shaft 28 upward a small distance until pivots 30 and 32 are above the line connecting pivots 42 and 44. This may be accomplished by means such as a compressed drive spring, not shown, which is compressed during the loading procedure described above.

As soon as pivots 32 and 34 reach a point above the line connecting pivots 42 and 44, compression springs 46 and 48, respectively, are free to unload fully, propelling thrust plate 18 and impact rod 16 in an upward direction. Both thrust plate 18 and impact rod 16 are maintained perpendicular to the longitudinal direction of travel by means of guide rails 22. Thrust plate 18 comes to a dead stop when it hits stop 56. However, due to the floating support of impact rod 16 by means of shouldered shaft 20, impact rod 16 moves with all its acquired inertia into impact with the bottom surface of piston 12.

The sum of the mass of piston 12 plus the equivalent mass due to the radiation reaction of the piston is made equal to the mass of impact rod 16 so that a maximum amount of energy is transferred from impact rod 16 to piston 12.

Since the contact surfaces of impact rod 16 and piston 12 are matched and are of equal area, the impact energy is distributed equally over the entire contact surface of the piston 12. Immediately after impact, since substantially all the energy of impact rod 16 is transferred to piston 12, impact rod 16 falls back into contact with thrust plate 18, thereby allowing piston 12 to vibrate freely.

The length of the longitudinal slot in hollow shaft 28 is longer than the length of travel of hollow shaft 28 after release from its loaded position, so that pin 54 does not 4 come in contact with the lower end of this longitudinal slot until after impact.

Although a novel spring-linkage has been provided as the drive mechanism in the described preferred embodiment of the invention, it may be replaced by a cylinder and a piston therein which is capable of being driven pneumatically or by an explosive mixture of gasses, or solid or liquid fuels.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invetnion may be practiced otherwise than as specifically described.

I claim:

1. An impact energized sound creating device comprising a housing having an opening in a wall thereof, a rigid piston disposed in said opening in the housing in which it is disposed, spring means bridging the space between the periphery of the piston and the periphery of said opening and supporting said piston for vibration in a direction axially of said opening, an impact rod within the housing behind said piston and having its end adjacent said piston of the smne face area and shape as the adjacent face of said piston and aligned therewith, a thrust plate within said housing behind said rod, means guiding said impact rod endwise toward and from said piston and also guiding said thrust plate in the same direction, said housing having a stop limiting movement of said plate toward said piston, said impact rod and plate having between them a lost motion connection in the direction of said movement, the extent of said lost motion being greater than the distance said rod travels to strike said piston after said plate engages said stop, means by which the plate may be drawn away from said stop a substantial distance and then released, and means acting on said plate and operable, when said plate is released after it is drawn away from said stop, to impel said plate and with it said rod toward said piston.

2. An impact energized sound creating device comprising a housing having an opening in a wall thereof, a rigid piston disposed in said opening in the housing in which it is disposed, spring means bridging the space between the periphery of the piston and the periphery of said opening and supporting said piston for vibration in a direction axiallly of said opening, an impact rod within the housing behind said piston and having its end adjacent said piston of approximately the same face area and shape as the adjacent face of said piston and aligned therewith, means guiding said impact rod endwise toward and from said piston, and means having a lost motion connection to said rod in the direction of its travel toward and from said piston, for withdrawing said rod away from said piston and then driving it toward said piston, means for stopping said last-named means in its drive toward said piston just immediately before said rod strikes said piston, said lost motion connection having suflicient play to enable said rod to continue alone far enough to strike said piston and rebound.

3. The device as set forth in claim 2 wherein said means with said lost motion connection includes an actuating element having a lost motion connection to said rod, and spring actuated toggle means connected to said element and stressed when said rod is withdrawn by said element in a direction away from said piston and which when released while urging said rod toward the piston will drive said rod toward said piston.

4. The device as set forth in claim 1 wherein said spring means is continuous between the piston and housing entirely around the piston, and said housing is closed and partially evacuated of air to reduce the cushioning effect of air between the engaging surfaces of said rod and said piston and thereby minimize the interval required to develop full impact pressure between said rod and piston.

5. The device as set forth in claim 1 wherein the inner face of said piston and the end face of the rod that engages with said piston have their engageable surfaces making full and even contact over their entire said adjacent engageable faces.

6. The device as set forth in claim 2 wherein said means with said lost motion connection includes an actuating element having :a lost motion connection to said piston, and a spring actuated toggle means connected to said element and stressed by movement of said element in a direction to Withdraw said rod away from said piston, and which when released while urging said rod toward said element and said piston will drive said rod toward said piston, said toggle means when stressed by movement of said element in a direction to withdraw said rod away from said piston being movable past a dead center position, and a stop limiting such movement beyond dead center position to a small extent beyond said dead center position, whereby said toggle means after it passes dead center while withdrawing said rod away from said piston, will be releaseably held in withdrawn position until pushed back through said dead center position when it is desired to have said rod strike said piston.

7. An impact energized sound creating device comprising a housing having an opening in its top, a rigid piston nearly filling said opening, flexible means connecting the periphery of said piston to the periphery of said opening and with the piston closing said opening, an impact rod below said piston and movable toward and from said piston, a thrust plate below said rod and having a lost motion connection to said rod, said housing having a stop abutment limiting movement of said plate toward said piston and with said lost motion connection having play sufficient for said rod to strike said piston after said plate engages said abutment, means for guiding said plate in a direction toward and from said piston, spring toggle means acting between said housing and plate for resiliently urging said plate toward said piston, and means for pulling said plate in a direction away from said piston to stress said toggle means, whereby when said pulling means releases said toggle means before it has passed a dead center position, said toggle means will drive said plate and through it said rod endwise to cause said rod to strike said piston.

8. The device as set forth in claim 7, wherein said pulling means is operable in a pulling direction until said toggle means just passes a dead center position, said housing having a stop part limiting further movement past dead center position in a pulling direction to hold the toggle means stressed, whereby when said plate is pushed toward said piston to carry said toggle means back through dead center position, said toggle means is free to operate said plate toward said piston and cause said rod to strike said piston.

9. An impact energized device for creating acoustic signals comprising a housing having an opening in a wall thereof, a rigid piston within and nearly filling said opening and disposed with its faces parallel to the plane of said opening, a ring spring connecting the periphery of said piston to the periphery of said opening, an impact rod in said housing and mounted for bodily, free floating, reciprocatory movement toward and from the piston, operating means having a limited lost motion connection to said rod and operable when free to impel it toward said piston, said operating means being operable in 'a direction away from said rod into a cocked position in which it is releasably held in such withdrawn position, stop means in the path of movement of said operating means and limiting movement of said operating means toward said piston to a position just before it forces said rod into contact with said piston, but sufficiently close to enable said rod, through said lost motion connection, to continue its movement independently of the operating means toward said piston freely and contact said piston within the limits permitted by the lost motion in said connection, said rod being free of any springs acting directly thereon, and means by which said operating means is released for operation toward said piston when sound is to be created. 10. The device as set forth in claim 9, wherein said spring ring is impervious and sealed to said housing opening and the periphery of said piston, and said housing is closed and partially evacuated to reduce the time interval required to develop full impact pressure upon impact.

11. The device as set forth in claim 9, wherein the impact faces between said rod and piston are planar and in face to face alignment, have substantially the same areas, and during impact of said rod on said piston have substantially uniform contact over their entire impact faces.

12. An impact energized device for creating acoustic signals of high intensity and short duration, which comprises a support having an opening, a rigid piston disposed in said opening with an exposed face from which a sound signal may be sent and which face is parallel to the plane of said opening, means interposed between the periphery of said piston and said support along the periphery of said opening for mounting said piston for reciprocation in a direction normal to its said face, an impact rod mounted in said support for reciprocatory movement toward and from said piston, said piston and rod having their entire adjacent faces of equal area, aligned face to face, parallel, and engageable with one another uniformly over substantially their entire adjacent face areas, driving means for said rod carried by said support for movement toward and from the end of said rod opposite from said piston and having a lost motion connection to said rod by which said rod may be driven toward said piston and enabling limited, free floating movement of the rod in a direction toward and from the piston separately from said driving means, means for limiting the advance of said driving means toward said piston and operable to stop movement of said driving means just before it forces said rod into engagement with the piston and said lost motion connection being sufficient in extent of said lost motion to enable free further advance of said rod, after' said driving means is stopped by said limiting means, into an impact contact with said piston and rebound therefrom.

13. An impact energized device for creating acoustic signals which comprises a support, a rigid, sound creating piston With parallel faces, means resiliently mounting the periphery of said piston on said support and enabling limited reciprocatory movement of said piston in a direction normal to its faces, an impact rod separate from said piston, means on said support mounting said rod for reciprocation endwise toward and from said piston, adjacent faces of said piston and rod being of approximately equal shape and area, aligned face to face, parallel to one another, and normal to the direction of movement of said rod, and upon movement of said rod into contact with the piston having their faces contacting uniformly over their entire face areas, and means having a spring actuated toggle device operable, when released, toward said impact rod and having a lost motion coupling to said rod enabling limited movement of said rod relatively to said toggle device in the direction of movement of said rod, said support having an abutment engaged by said toggle device just before said rod impacts said piston, and said lost motion connection being sufficient in extent to enable continued movement of said rod into impact with said piston after said toggle device is stopped by said abutment following its release and movement toward said piston for causing said rod to impact strongly against said piston and rebound therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 1,191,948 Coates July 25, 1916 1,611,740 Hahnemann Dec. 21, 1926 1,689,574 Williams Oct. 30, 192.8 1,753,368 Du Bois-Reymond Apr. 8, 1930 2,044,820 Turner June 23, 1936 2,087,811 Patrick July 20, 1937 

